Method of using integrated electro-microfluidic probe card

ABSTRACT

A method includes mounting an integrated electro-microfluidic probe card to a device area on a bio-sensor device wafer, wherein the electro-microfluidic probe card has a first major surface and a second major surface opposite the first major surface. The method further includes electrically connecting at least one electronic probe tip extending from the first major surface to a corresponding conductive area of the device area. The method further includes stamping a test fluid onto the device area. The method further includes measuring via the at least one electronic probe tip a first electrical property of one or more bio-FETs of the device area based on the test fluid.

PRIORITY CLAIM

The present application is a continuation of U.S. application Ser. No.15/350,399, filed Nov. 14, 2016, which is a divisional of U.S.application Ser. No. 13/673,602, filed Nov. 9, 2012, now U.S. Pat. No.9,523,642, issued Dec. 20, 2016, which are incorporated herein byreference in their entireties.

FIELD

This disclosure relates to methods for forming and for testingbiosensors on a chip. Particularly, this disclosure relates to systemsand methods for testing biological field-effect-transistors (bioFETs)and methods for forming them.

BACKGROUND

Biosensors are devices for sensing and detecting biomolecules andoperate on the basis of electronic, electrochemical, optical, andmechanical detection principles. Biosensors that include transistors aresensors that electrically sense charges, photons, and for mechanicalproperties of bio-entities or biomolecules. The detection can beperformed by detecting the bio-entities or biomolecules themselves, orthrough interaction and reaction between specified reactants andbio-entities/biomolecules. Such biosensors can be manufactured usingsemiconductor processes, can quickly convert biomolecular information toelectric signals, and can be easily applied to integrated circuits (ICs)and microelectromechanical systems (MEMS).

BioFETs (biological field-effect transistors, biologically sensitivefield-effect transistors, biologically active field-effect transistors,or bio-organic field-effect transistors) are a type of biosensor thatincludes a transistor for electrically sensing biomolecules orbio-entities. While BioFETs are advantageous in many respects,challenges in their fabrication and/or operation arise, for example, dueto compatibility issues between the semiconductor fabrication processesand biological applications.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1 is a schematic of an embodiment of a wafer-level biosensorprocessing tool according to one or more aspects of the presentdisclosure.

FIG. 2 is cross-sectional views of an integrated electro-microfluidicprobe card and portion of a BioFET according to one or more aspects ofthe present disclosure.

FIGS. 3 and 4 are perspective views of integrated electro-microfluidicprobe cards according to one or more embodiments of the presentdisclosure.

FIGS. 5 and 6 are flow charts of method embodiments for testing andfabricating a BioFET device according to various aspects of the presentdisclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Moreover,the formation of a first feature over or on a second feature in thedescription that follows may include embodiments in which the first andsecond features are formed in direct contact, and may also includeembodiments in which additional features may be formed interposing thefirst and second features, such that the first and second features maynot be in direct contact. Further still, references to relative termssuch as “top”, “front”, “bottom”, and “back” are used to provide arelative relationship between elements and are not intended to imply anyabsolute direction. Various features may be arbitrarily drawn indifferent scales for simplicity and clarity.

In a biological field-effect transistor (BioFET), the gate of ametal-oxide-semiconductor field-effect transistor (MOSFET), whichcontrols the conductance of the semiconductor between source and draincontacts, includes a bio- or biochemical-compatible layer or abiofunctionalized layer of immobilized probe molecules that act assurface receptors. Essentially, a BioFET is a field-effect biosensorwith a semiconductor transducer. An advantage of BioFETs is the prospectof label-free operation. Specifically, BioFETs enable the avoidance ofcostly and time-consuming labeling operations such as the labeling of ananalyte with, for instance, fluorescent or radioactive probes. When alabeled analyte reacts as designed and emits fluorescence orradioactivity, the emission is short-lived and thus has a shortmeasurement window of opportunity. However, even with these cost,time-consumption, and design constraints, use of the labeled analyteprovides a good quantification of a reaction and may be appropriate insome circumstances, for example, for benchmarking a new biosensor.

A typical detection mechanism for BioFETs is the conductance modulationof the transducer due to the binding of a target biomolecule orbio-entity to a sensing surface or a receptor molecule immobilized onthe sensing surface of the BioFET. When the target biomolecule orbio-entity is bonded to the sensing surface or the immobilized receptor,the drain current of the BioFET is varied by the potential from thesensing surface. This change in the drain current can be measured andthe bonding of the receptor and the target biomolecule or bio-entity canbe identified. Many biomolecules and bio-entities may be used tofunctionalize the sensing surface of the BioFET such as ions, enzymes,antibodies, ligands, receptors, peptides, oligonucleotides, cells oforgans, organisms and pieces of tissue. For instance, to detect ssDNA(single-stranded deoxyribonucleic acid), the sensing surface of theBioFET may be functionalized with immobilized complementary ssDNAstrands. Also, to detect various proteins such as tumor markers, thesensing surface of the BioFET may be functionalized with monoclonalantibodies.

One difference in various types of BioFETs is the location of thesensing surface. One example of a sensing surface is a top of a floatinggate connected to the gate of the BioFET. In other examples of sensingsurfaces, the biomolecules bind directly or through receptors on thegate or the gate dielectric of the BioFET. These BioFETs directly sensethe target biomolecules and are more accurate than those having asensing surface on a floating gate.

A BioFET device may include a number of BioFETs and other transistorsand circuitry. Each of the BioFETs has a sensing surface associated witha microfluidic channel or well where a biological matter may flow and besensed. A BioFET device may be manufactured by several entities andassembly/testing may be performed by yet other entities. In a typicalscenario, the transistors including BioFETs and non-bio FETs aremanufactured on a semiconductor substrate in a semiconductormanufacturing fabrication facility using complementarymetal-oxide-semiconductor (CMOS) process compatible techniques. In someembodiments, the microfluidic structures on the BioFET device are formeddirectly on the substrate after the transistors and circuits are formed.In some embodiments, the microfluidic structures on the BioFET deviceare formed separately and attached at the semiconductor manufacturingfabrication facility. In some embodiments, the microfluidic structureson the BioFET device are formed separately and attached at anotherfacility, which may be a customer or a vendor of the semiconductormanufacturing fabrication facility.

A semiconductor manufacturing fabrication facility is equipped toperform chip level, wafer level, and wafer level chip scale testing forthe semiconductor devices produced at the fabrication facility. Ageneral semiconductor probe station usually includes micromanipulatorsor probe cards for electrical probing of a partially or fully fabricateddevice. If any defects are found, the product may be reworked or markedbefore shipping. However, traditional semiconductor probe stations arenot equipped to test BioFET devices under operating conditions. Whilethe basic electrical properties may be tested, the portions of theBioFET devices used with biological fluids, such as sensing surfaces andmicrofluidic channels, cannot be tested using a traditionalsemiconductor probe station.

In a biological laboratory, a sample delivery system usually uses anarray of pipette tips or a printer head to transfer biological samplesonto a specimen on a target with fixed dimensions, for example, a 96well-plate. One or more fluid supplies are connected to deliverypipettes that inject the fluid into a container, usually a test tube orwells on a plate. Either the container or the pipettes move relative tothe other. A sample delivery system may involve several pipettes thatcan simultaneously deliver fluid to multiple containers. Some pipettesmay also pick up fluid from one container and deliver the fluid toanother container.

The present disclosure provides a system for wafer level chip scalepost-processing and testing of BioFET devices, such as a Lab-On-Chipdevice. The ability to verify functionality and yield of a BioFET devicewithout shipping for testing to be performed at a customer site andresultant delays makes mass production of biomedical devices in asemiconductor foundry possible. A wafer-level biosensor processing toolcan integrate post-processing (sensing surface functionalization, sampledelivery) and testing (optical probing for fluidic dynamics andbiological reactions; electrical probing for device characteristics).The wafer-level biosensor processing tool can monitor the biologicalreactions via an attached microscope in real-time. The wafer-levelbiosensor processing tool allows testing and diagnostics/troubleshooting, if a problem is detected. The wafer-level biosensor processingtool also expedites feedback to the manufacturer of BioFET devices.

The present disclosure provides a wafer-level biosensor processing toolthat combines the various functions for electrical and biologicalprocessing and testing on one platform. FIG. 1 is a schematic diagram ofa wafer-level biosensor processing tool 100 in accordance with variousembodiments of the present disclosure. The wafer-level biosensorprocessing tool 100 may be enclosed in a chamber to allow forenvironmental control. For example, the various processing and testingmay be performed in a temperature or pressure environment different fromthe ambient. The chamber may include gas inlets and outlets to controlan atmospheric composition during processing and testing. For massproduction, load locks and automated wafer carrier/cassette handling mayalso be incorporated into the wafer-level biosensor processing tool 100.

When a wafer enters the wafer-level biosensor processing tool 100, theBioFETs and circuitry are already formed. A wafer 113 is positioned on awafer stage 103 in the tool 100. The wafer 113 is shown in dotted linesbecause it is not a part of the wafer-level biosensor processing tool100 during a non-operating state. The wafer 113 may be positioned by awafer transfer robot arm (not shown) or the wafer may be manually placedby an operator. The wafer stage 103 is at least partially transparent,to allow light from a light source 109 to transmit light through thewafer stage during operation. The wafer stage 103 may be a pedestal, asusceptor, or a carousel where more than one wafer or workpiece may beprocessed or tested at the same time. The wafer stage 103 may be movedin one or many directions. According to various embodiments, the waferstage 103 has freedom of motion in at least 2 directions: x and y. Insome embodiments, the wafer stage 103 may be moved in 3 directions x, y,and z; x, z, and e (theta) (rotational); or x, y, and e (rotational).The wafer stage 103 may also include an embedded temperature controlincluding sensors and a heater/cooler configured to change thetemperature of the wafer 113 by conductive heating or cooling. In someembodiments, the wafer stage 103 may accommodate a portion of a wafer(partially diced), a die, a number of dies on a package substrate, or apackaged chip.

The wafer-level biosensor processing tool 100 also includes anintegrated electro-microfluidic probe card 101 positioned over the waferstage 103. The integrated electro-microfluidic probe card 101 includes afluidic mount 121 containing one or more fluidic probes 127 and one ormore electrical probes 123. The fluidic mount 121 includes at least oneset of fluid inlet and outlet 117 that accepts test fluid or processfluid from a fluid supply 115 and returns used fluid to a fluid return116. FIGS. 2-4 show different embodiments of the integratedelectro-microfluidic probe card and various features of the integratedelectro-microfluidic probe card will be discussed in more detail.

The integrated electro-microfluidic probe card 101 also includes one ormore handle lugs 119 attached to an edge portion or a side portion ofthe integrated electro-microfluidic probe card 101. The integratedelectro-microfluidic probe card 101 may be held and moved by one or morecard fixture arms 125 or by a micromanipulator arm using one or more ofthe handle lugs 119. During operation, the card fixture arms 125 exertdownward pressure on the integrated electro-microfluidic probe card 101so that the fluidic probe 127 seals against the wafer 113. Thus, thecard fixture arm 125 is configured to move the integratedelectro-microfluidic probe card 101 in at least a downward direction.According to various embodiments, the card fixture arm 125 has movablejoints and/or a base capable of moving laterally as well as vertically.

According to various embodiments, the integrated electro-microfluidicprobe card 101 is at least partially transparent such that a microscope111 positioned over the integrated electro-microfluidic probe card 101may observe bio-reactions on the wafer 113 through the fluidic mount121. The handle lugs 119 are positioned so as not to obstruct thepropagation of light to microscope 111. At least a portion of thefluidic mount 121 over the fluidic probe 127 is transparent. Lightsource 107 over the microscope 111 can be used to illuminate the waferthrough the integrated electro-microfluidic probe card 101 or to triggerfluorescence or phosphorescence by radiating labels in the analyte withlight at a specific wavelength.

The microscope 111 may be mounted to a camera capable of recording andmeasuring various optical aspects of an image captured using themicroscope. Further, the microscope 111 may be moved independently fromthe wafer stage 103 and the integrated electro-microfluidic probe card101 so as to focus on just a portion of a viewable area of the waferstage through the transparent fluidic mount 121.

The wafer-level biosensor processing tool 100 also includes one or moremicromanipulators 105 that can hold various probing tools, for instance,needles, scribes, nozzles, pipette tips or electrodes. Through theprobing tools, small quantities of processing fluid or testing fluid maybe added or extracted from the wafer 113. The micromanipulators 105 maybe controlled through an operator interface and has enough precision ofmovement to target a small area of a BioFET device being diagnosed. Forexample, if a BioFET fails a test, a small amount of etchant may beadded to remove a layer from a surface of the wafer or to remove aportion of a sensing surface to further diagnose the reason for thefailure. The micromanipulator 105 may work in concert with themicroscope 111. For example, the micromanipulator 105 may be calibratedby dropping a fluid at a specified area on the wafer stage 103, the dropmay be verified automatically by the camera attached to the microscope111. In another example, an operator may remove a portion of a layer ofmaterial by sawing or scribing with the micromanipulator 105 and verifythe results by viewing through the microscope 111.

FIG. 2 includes cross-section diagrams of an integratedelectro-microfluidic probe card 201 and a portion 221 of the wafer 113.The integrated electro-microfluidic probe card 201 includes a fluidicmount 217. The fluidic mount 217 has a major surface 251 facing thewafer portion 221 and another major surface 253 facing away from thewafer portion 221. One or more electric probes 213 and one or morefluidic probes 209 are formed or mounted on the major surface 251. Oneor more handle lugs 215 is formed or mounted on the other major surface253 near the edges or on a minor surface 255 so as to not obstruct aview of the wafer portion 221 from the major surface 253. At least oneelectronic port (not shown), at least one fluid input 203 and at leastone fluid output 205 are disposed on the minor surfaces 255. The use ofwords “major” and “minor” does not imply that the surface area of amajor surface is necessarily larger than that of a minor surface.Rather, the words are used to distinguish surfaces that either facetoward or away from the wafer and the surfaces that are normal to thewafer.

The electric probe 213 includes an electronic probe tip of a conductingmaterial and a base for supporting the electronic probe tip and forelectrically connecting the electronic probe tip to the electronic porton the fluid mount 217. The electronic probe tip may be made of a metaland may comprise a flexible material or a joint. The conducting materialat the electronic probe tip is configured to make electrical contactwith a contact pad 223 on a surface of the wafer portion 221 using acontact area smaller than the area of the contact pad 223.

Internal to the fluidic mount 217 are microfluidic channels 207 thatroutes fluids from the fluidic input 203 through the fluidic probe 209to the fluidic output 205. Microfluidic channels 207 may include valves,pumps, heaters, or other devices in contact with the fluid that cancontrol or direct the fluid. Other devices may include variouselectrodes that can increase, decrease, or deflect flow of the fluid.Examples are magnets or ferromagnets or electrodes for magnetophoresis,metal electrodes for electrophoresis, or particular dielectric materialfor dielectrophoresis. The valves, pumps, and heaters may bemicroelectromechanical systems (MEMS). The microfluidic channels 207 mayalso include various sensors or microsensors such as pressure sensors,flow meters, temperature sensors, and electrical sensors coupled to thefluid flow.

The fluidic probe 209 includes conduits 211 for conducting fluid to andfrom the wafer portion 221 to be tested. During testing or processing,the integrated electro-microfluidic probe card 201 is positioned overthe wafer portion 221 so that the electric probes 213 on the integratedelectro-microfluidic probe card 201 are aligned with the metal pads 223on the wafer portion 221 and the fluidic probe 209 is aligned with aBioFET well 229 on the wafer portion 221. The integratedelectro-microfluidic probe card 201 is then mounted with the wafer 221either by moving the wafer stage up or lowering the integratedelectro-microfluidic probe card 201 to create a seal between the fluidicprobe 209 and the BioFET well 229. In order to create a seal, thefluidic mount 217 and/or the fluidic probe 209 may deform. However, thefluidic mount 217 and the fluidic probe 209 are designed to return totheir original shape after dismounting from the wafer so they may bere-used.

The fluidic mount 217 and the fluidic probe 209 may be formed ofsilicone, epoxy, or photoresist. In some embodiments, the fluidic mount217 and the fluidic probe 209 may be formed of polydimethylsiloxane(PDMS) or polymethylmethacrylate (PMMA). In certain embodiments, thefluidic mount 217 and the fluidic probe 209 are made of the samematerial, which is bio-compatible and may be re-usable. In someembodiments, the material is molded.

The wafer portion 221 is formed on a substrate 225 which includesinterconnect structure 231 having electrical contact pads 223 andsensing surface 233 within a microfluidic structure 227 enclosing amicrofluidic well 229. The microfluidic structure 227 is formed abovethe sensing surface 233. In some embodiments, the microfluidic structure227 may have different shapes depending on the placement of the sensingsurface 233. For example, in some embodiments, the sensing surface 233is at or close to a gate of a BioFET; allowing the microfluidicstructure 227 to be embedded in the interconnect structure.

In some embodiments, a fluidic mount template is formed having thevarious electric probes, electronic port, fluid input and outputs, andhandle lugs. Recesses on the same side of the electric probes areprepared. The fluidic probe inserts are designed to complement thedesign of the microfluidic structure on the BioFET device. For example,if a well structure having inlet and outlet is available on the BioFETdevice, then a conduit type fluidic probe such as fluidic probe 209 ofFIG. 2 is used. If no microfluidic structure is available on the BioFETdevice, then a well-type fluidic probe is used, where the fluidic probesurrounds and covers the sensing surface on the BioFET. Using recesseson a fluidic mount allows the same fluidic mount to be used for morethan one BioFET device layout. Using recesses also allows the fluidicprobes to be removed for cleaning. In other embodiments, themicrofluidic mount and the fluidic probes are formed for each BioFETdevice.

The wafer portion 221 may include one BioFET device, a portion of aBioFET device, or multiple BioFET devices. In some embodiments, theintegrated electro-microfluidic probe card 201 has many fluidic probesand electronic probes at different locations to test more than oneBioFET device with one integrated electro-microfluidic probe cardsimultaneously. On the other hand, a simple integratedelectro-microfluidic probe card 201 with one or a few fluidic probes andone or a few electronic probes may be used to test similarly dimensionedBioFET devices separately. In one example, an integratedelectro-microfluidic probe card has a fluidic mount having recesses forthe fluidic probes. Depending on the number of BioFETs to be tested andthe locations of the BioFETs, the recesses may be configured with afluidic probe or a blank flange that covers the recesses where notesting is intended. In some embodiments, additional electronic probesare added or removed. Such integrated electro-microfluidic probe cardmay be a generic card capable of testing different BioFET devices.

FIGS. 3 and 4 are both perspective views of integratedelectro-microfluidic probe card embodiments 300 and 400. In FIG. 3 , theintegrated electro-microfluidic probe card 300 includes fluidic mount301 having a window 313 through which the microscope 111 (FIG. 1 ) mayrecord or observe reactions. Because an observation window is used, thefluidic mount 301 may or may not be transparent. Handle lugs 303 areattached on a top surface of the fluidic mount 301. Electronic ports 311are also formed on the top surface of fluidic mount 301. In otherembodiments, the handle lugs and the electronic port may be on a minorsurface normal to the wafer 113 (FIG. 1 ). Fluid input and output 305 isformed on the minor surface. Even though only one fluid input and outputare shown on each minor surface, additional fluid inputs and outputs onthe fluid mount 301 are possible. Further, the fluid input and output305 may be on the same side or different sides of the fluid mount 301.On the major surface closest to the wafer, fluidic probes 309 andelectronic probes 307 are disposed. In some embodiments, the electronicprobes 307 are flexible to make reliable electrical contact with thecontact pads 223 (FIG. 2 ) on the wafer. In certain embodiments, theelectronic probes may be mechanically actuated to contact differentcontact pads 223 on the wafer through movement of one or more joints ona micromanipular arm. In addition to sensing electrical properties, theelectronic probes may be used to provide a bias voltage or a current.

In FIG. 4 , the integrated electro-microfluidic probe card 400 includesfluidic mount 401 having a window 413 through which the microscope 111(FIG. 1 ) may record or observe reactions. Because an observation windowis used, the fluidic mount 401 may or may not be transparent. In theembodiment of FIG. 4 , the fluidic probe 409 is transparent to allowobservation. Handle lugs 403 are attached on a top surface of thefluidic mount 401 in this embodiment. In other embodiments, the handlelugs 403 are attached on a minor surface normal to the wafer 113 (FIG. 1). In some embodiments, fluid input and outputs 405 and electronic port411 are formed on the minor surface of fluidic mount 401. Even thoughthree fluid input and outputs 405 are shown, additional fluid inputoutputs are possible, in some embodiments. The fluidic mount 401 in thisembodiment is in the shape of a cylinder and has only one minor surface.On the major surface closest to the wafer 113, one or more fluidicprobes 409 and electronic probes 407 are disposed. In some embodiments,the electronic probes 407 are flexible to make reliable electricalcontact with the contact pads 223 (FIG. 2 ) on the wafer. In certainembodiments, the electronic probes 407 are mechanically actuated tocontact different contact pads on the wafer 113 through movement of oneor more joints on a micromanipular arm. In addition to sensingelectrical properties, the electronic probes 407 may be used to providea bias voltage or a current.

FIGS. 5 and 6 are process flow diagrams for testing and processing apartially or fully fabricated BioFET device in accordance with variousembodiments of the present disclosure. FIG. 5 is process flow diagram ofmethod 500 for testing a partially fabricated or fully fabricated BioFETdevice. In operation 502 an integrated electro-microfluidic probe cardis formed. This operation may be performed by the facility testing theBioFET device, which also may be the same facility that manufactured theBioFET device. The integrated electro-microfluidic probe card may alsobe formed by a separate facility, for example, a customer of themanufacturer. As discussed, the integrated electro-microfluidic probecard may include various operational mechanisms (for example, MEMS) toallow for diagnostic examination in addition to testing.

In operation 504, the workpiece is aligned on a stage of a wafer-levelbiosensor processing tool. The workpiece includes the partiallyfabricated or fully fabricated BioFET device. The workpiece may be inthe shape of a wafer, a portion of a wafer (partially diced), a die, anumber of dies on a package substrate, or a packaged chip. While thedescriptions of a wafer-level biosensor processing tool herein focuseson wafer processing, the concepts discussed may be applied to otherworkpiece shapes and types. In some embodiments, the alignment isconfirmed optically or mechanically using an alignment mark orindentation on the workpiece.

In operation 506, an integrated electro-microfluidic probe card ismounted to a device area of the workpiece. As discussed, the mountingincludes either the integrated electro-microfluidic probe card movingtoward the workpiece or the workpiece to moving toward the integratedelectro-microfluidic probe card. When mounted, the one or more fluidicprobes on the integrated electro-microfluidic probe card seals against aportion of the device area of the workpiece, usually at a sensingsurface, e.g., sensing surface 233 (FIG. 2 ), that may or may notinclude contact at a microfluidic structure. Further, electronic probes,e.g., electronic probes 213 (FIG. 2 ), on the integratedelectro-microfluidic probe card also makes electrical contact withcontact pads on workpiece.

In operation 508, a test fluid to flowed to the integratedelectro-microfluidic probe card. In some embodiments, the test fluid isflowed through one or more fluid inputs, e.g., fluid input 203 (FIG. 2). The test fluid may include a biological matter or a proxy for abiological matter to test the BioFETs. The various flow mechanisms onthe integrated electro-microfluidic probe card may pump and direct thetest fluid toward one or more microfluidic wells or channels having thesensing surface. Further, in operations 510 and 512 the wafer may beexposed to light and a fluid property or light radiation level may bemeasured through a transparent fluidic mount or an observation window inthe fluidic mount. For example, two test fluids may be added and mixedin a microfluidic well over the sensing surface. A microscope, e.g.,microscope 111 (FIG. 1 ), may record the extent of the reaction bymeasuring a light radiation level at a particular frequency, forexample, the reaction may result in a photon emission after irradiationthat are measured by the microscope through the transparent fluidicmount or through the observation window.

In operation 514, changes to one or more BioFETs based on the test fluidflow are measured via the one or more electronic probe tips. The testfluid includes material that when attached to the sensing surface,changes the electrical properties of the BioFET. The electronic probetips may measure a current or a voltage while optionally applying avoltage or current. In some embodiments, the electronic probe tip sensesa difference in current through the BioFET before and after the testfluid flow. The sensed change is compared against an expected result asdesigned and may also be compared against an expected result based onthe optical measurement from the microscope. If the sensed changematches the expected results, then the BioFET device performed properlyas designed and manufactured and passes the test.

In some embodiments, the electronic probe tip provides power to theBioFET device for the BioFET device to conduct testing and analysis ofthe test fluid. The test results are provided to the wafer-levelbiosensor processing tool and compared against the expected results. Inthis case, signal processing and further operation are performed by theBioFET device before the test result is provided. The BioFET device maybe pre-programmed with a number of the testing and analysis programsthat are activated by the wafer-level biosensor processing tool,depending on the objective of the test. For example, one test may focuson the ability of the sensing surface to retain receptors. A test fluidthat includes a marker or stain detectable by microscope with a highaffinity for the receptors may be used to test the sensing surface. Themicroscope data is compared against the data from the electronic probetips to verify whether the receptors are attached to the sensingsurface. Another test may focus on the sensitivity of the transistorgate to a small change in a number of bound markers. Many test programsmay be devised and results can be used to adjust the BioFET devicedesign and/or the manufacturing process.

In operation 516, the test fluid may be flushed from the integratedelectro-microfluidic probe card after testing and reading. The flush mayinclude vacuuming, adding a stream of cleaning fluid, for example,deionized water, an inert fluid, or gas, and drying. In some cases whenbiological material is used for testing, the fluidic channels in thefluidic mount and the BioFET device are rinsed and cleaned beforefurther processing. Some receptors on the sensing surface may requirewetting or other preservation technique to prevent degradation ordetachment during shelving or shipping.

In operation 518, the BioFET device may be marked as pass or “not pass”based on the performance of the BioFET during the testing process. Themarking may be physical by scribing or otherwise making a mark on theBioFET device. The marking may also be not physical, for example, bynoting the lot and location of the defect into a database. A markedBioFET device may undergo further processing to correct a detectedproblem, if possible, or be removed from the manufacturing process.

In operation 520, the integrated electro-microfluidic probe card isdismounted from the device area and moved to the next device area. Ifthe integrated electro-microfluidic probe card has already tested allthe devices on the wafer, then the integrated electro-microfluidic probecard moved to a home position away from the wafer. In some embodiments,only certain test devices on the wafer are used for method 500. Forexample, some BioFET device designs are intended as single-use andtesting would be limited to a few test BioFET devices on the wafer thatrepresent the yield of the rest of the wafer. For more complex designsthat are re-usable or to verify the manufacturing process, every BioFETdevice may be tested.

The method 500 includes some optional operations. For example, theoperation 502 of forming the integrated electro-microfluidic probe cardmay be performed by another facility. In some cases, a genericintegrated electro-microfluidic probe card may be used. Operations 510and 512 of using optical measurements may be omitted if a marker used isnot photo-luminescent or has other photo-detectible characteristic, suchas staining. Flushing the test fluid from the BioFET device and theintegrated electro-microfluidic probe card may be omitted if the BioFETis a single use BioFET. After dismounting the integratedelectro-microfluidic probe card from the wafer, the integratedelectro-microfluidic probe card may not move to another location on thetest workpiece. As discussed, the workpiece may not be a whole waferhaving many devices thereon.

The method 500 includes some optional loops. For example, more than onetest may be performed by flowing different test fluid or changing thetest fluid flow properties after operation 516 by following the dottedline back to operation 508. More than one device area may be testedafter operation 520 by following the dotted line to operation 506.

In addition to testing, the wafer-level biosensor processing tool mayalso be used to perform some processing such as building desirablechemistry on sensing surfaces, such as coating and attaching receptors,and on other flow surfaces in the microfluidic structure. FIG. 6 is aprocess flow diagram of method 600 for post fabrication processing onBioFET devices. In operation 602, an integrated electro-microfluidicprobe card is formed. As discussed, the integrated electro-microfluidicprobe card may include various operational mechanisms (for example,MEMS).

In operation 604, the workpiece is aligned on a stage of a wafer-levelbiosensor processing tool. The workpiece includes the partiallyfabricated or fully fabricated BioFET device. The workpiece may be inthe shape of a wafer, e.g., wafer 113 (FIG. 1 ), a portion of a wafer,e.g., wafer portion 221 (FIG. 2 ) (partially diced), a die, a number ofdies on a package substrate, or a packaged chip. The alignment may beconfirmed optically or mechanically using an alignment mark orindentation on the workpiece. In operation 606, an integratedelectro-microfluidic probe card is mounted to a device area of theworkpiece. This operation is the same as operation 506 of FIG. 5 .

In operation 608, a fluid is stamped or printed in the device area ofthe workpiece. In some embodiments, the fluidic probe forms a seal onthe device area surface to effectively form a pattern on the surfacewhen a fluid flows through the fluidic probe. The fluidic probe mayinclude additional patterns on the surface of the fluidic probecontacting the device area. One or more fluids may be appliedalternatingly or serially to achieve a desirable chemistry. In certainembodiments, the fluidic probe may include nozzles similar to a printerhead that can release a set amount of fluid in an area defined by thefluidic probe. In one example, a self-aligned monolayer of receptors maybe applied by printing onto a device area surface. In yet otherembodiments, a stamping effect is achieved by patterning a surface ofthe fluidic probe such that one or more portions of the surface iswettable by a fluid and other portions of the surface are not wettable.The fluidic probe surface is then exposed to the fluid and the patternedtransferred to the device area surface by stamping. Another stampingeffect may be to use a fluid permeable material as the fluidic probesurface and patterning a portion of the surface so that it is notpermeable by the fluid. One example is to use a porous dielectricmaterial as the fluidic probe surface and coating a portion of it in apattern with a non-porous material. When the fluid flows through theintegrated electro-microfluidic probe card that is mounted on the devicearea, the fluid flows through the porous material and imprints a patternon the device area surface. One skilled in the art may design a fluidprobe that can stamp or print a pattern onto a device area using one ormore of the techniques discussed or other techniques known to oneskilled in the art.

In operation 610, the fluid may be flushed from the integratedelectro-microfluidic probe card. As discussed in association withoperation 516 of FIG. 5 , a flush may involve various fluids and gases.If the stamping or printing requires multiple applications usingdifferent fluids, then the fluid is changed in operation 612. In someembodiments, the sensing surface on the device area may be treated firstusing one fluid and chemistry, and receptors attached using anotherfluid and chemistry. For example, in order to use self-assembledmonolayer (SAM) of molecules, a first step may be to stamp a pattern totreat the sensing surface. A next step may be to attach head groups ofsilane groups, silyl groups, silanol groups, phosphonate groups, aminegroups, thiol groups, alkyl groups, alkene groups, alkyne groups, azidogroups, or epoxy groups. After the head groups are formed then, thereceptors are attached to the head groups of SAM. If the fluid ischanged in operation 612, then the process follows the dotted line backto operation 608.

In operation 614, the integrated electro-microfluidic probe card isdismounted from the device area and moved to the next device area.Operation 614 is the same as operation 520 of FIG. 5 .

An aspect of this description relates to a method. The method includesmounting an integrated electro-microfluidic probe card to a device areaon a bio-sensor device wafer, wherein the electro-microfluidic probecard has a first major surface and a second major surface opposite thefirst major surface. The method further includes electrically connectingat least one electronic probe tip extending from the first major surfaceto a corresponding conductive area of the device area. The methodfurther includes stamping a test fluid onto the device area. The methodfurther includes measuring via the at least one electronic probe tip afirst electrical property of one or more bio-FETs of the device areabased on the test fluid. In some embodiments, electrically connectingthe at least one electronic probe tip to the corresponding conductivearea includes electrically connecting the at least one electronic probetip to a location beyond a boundary of the test fluid. In someembodiments, the method further includes marking the device area basedon results of the measuring of the first electrical property. In someembodiments, the marking includes physically marking the device area. Insome embodiments, the marking includes tracking a location of the devicearea. In some embodiments, the method further includes removing thedevice area from a manufacturing process in response to marking thedevice area as not passing. In some embodiments, the method furtherincludes further processing the device area in response to marking thedevice area as not passing.

An aspect of this description relates to a method. The method furtherincludes mounting an integrated electro-microfluidic probe card to adevice area on a bio-sensor device wafer, wherein theelectro-microfluidic probe card has a first major surface and a secondmajor surface opposite the first major surface. The method furtherincludes electrically connecting an electronic probe tip extending fromthe first major surface of the integrated electro-microfluidic probecard to a conductive area of the device area. The method furtherincludes printing a test fluid onto the device area. The method furtherincludes measuring via the electronic probe tip a first electricalproperty of one or more bio-FETs of the device area based on the testfluid. In some embodiments, the method further includes dismounting theintegrated electro-microfluidic probe card from the device areafollowing the measuring. In some embodiments, the measuring includesexposing the device area to light radiation. In some embodiments, themethod further includes marking the device area based on results of themeasuring of the first electrical property. In some embodiments, themethod further includes removing the test fluid from the device area. Insome embodiments, removing the test fluid includes removing the testfluid using a fluid or a gas.

An aspect of this description relates to a method. The method furtherincludes mounting an integrated electro-microfluidic probe card to adevice area on a bio-sensor device wafer, wherein theelectro-microfluidic probe card has a first major surface and a secondmajor surface opposite the first major surface. The method furtherincludes electrically connecting at least one electronic probe tipextending from the first major surface to a corresponding conductivearea of the device area. The method further includes placing a firsttest fluid on the device area, wherein the placing of the test fluidcomprises stamping or printing. The method further includes measuringvia the at least one electronic probe tip a first electrical property ofone or more bio-FETs of the device area based on the first test fluid.In some embodiments, the method further includes removing the first testfluid from the device area following the measuring. In some embodiments,the method further includes placing a second test fluid on the devicearea, wherein the second test fluid is different from the first testfluid. In some embodiments, placing of the second test fluid includesstamping or printing the second test fluid. In some embodiments, themethod further includes measuring via the at least one electronic probetip a second electrical property of the one or more bio-FETs of thedevice area based on the second test fluid. In some embodiments, themethod further includes marking the device area based on results of themeasuring of the first electrical property and the measuring of thesecond electrical property. In some embodiments, the marking includesphysically marking the device area.

In describing one or more of these embodiments, the present disclosuremay offer several advantages over prior art devices. In the discussionof the advantages or benefits that follows it should be noted that thesebenefits and/or results may be present is some embodiments, but are notrequired in every embodiment. Further, it is understood that differentembodiments disclosed herein offer different features and advantages,and that various changes, substitutions and alterations may be madewithout departing from the spirit and scope of the present disclosure.

What is claimed is:
 1. A method comprising: mounting an integratedelectro-microfluidic probe card to a device area on a bio-sensor devicewafer, wherein the electro-microfluidic probe card has a first majorsurface and a second major surface opposite the first major surface, andthe electro-microfluidic probe card comprises a transparent portion;electrically connecting at least one electronic probe tip extending fromthe first major surface to a corresponding conductive area of the devicearea; stamping a test fluid onto the device area, wherein the stampedtest fluid is removable; measuring via the at least one electronic probetip a first electrical property of one or more bio-FETs of the devicearea based on the test fluid; and flushing the stamped test fluid toremove the stamped test fluid from the device area.
 2. The method ofclaim 1, wherein electrically connecting the at least one electronicprobe tip to the corresponding conductive area comprises electricallyconnecting the at least one electronic probe tip to a location beyond aboundary of the test fluid.
 3. The method of claim 1, further comprisingmarking the device area as passing or not passing based on results ofthe measuring of the first electrical property.
 4. The method of claim3, wherein the marking comprises physically marking the device area. 5.The method of claim 3, wherein the marking comprises tracking a locationof the device area.
 6. The method of claim 3, further comprisingremoving the device area from a manufacturing process in response tomarking the device area as not passing.
 7. The method of claim 3,further comprising further processing the device area in response tomarking the device area as not passing.
 8. A method comprising: mountingan integrated electro-microfluidic probe card to a device area on abio-sensor device wafer, wherein the electro-microfluidic probe card hasa first major surface and a second major surface opposite the firstmajor surface, and the electro-microfluidic probe card comprises atransparent portion; electrically connecting an electronic probe tipextending from the first major surface of the integratedelectro-microfluidic probe card to a conductive area of the device area;printing a test fluid onto the device area, wherein the printed testfluid is removable; measuring via the electronic probe tip a firstelectrical property of one or more bio-FETs of the device area based onthe test fluid; and flushing the printed test fluid to remove theprinted test fluid from the device area.
 9. The method of claim 8,further comprising dismounting the integrated electro-microfluidic probecard from the device area following the measuring.
 10. The method ofclaim 8, wherein the measuring comprises exposing the device area tolight radiation.
 11. The method of claim 8, further comprising markingthe device area based on results of the measuring of the firstelectrical property.
 12. The method of claim 8, further comprisingprinting a second test fluid on the device area.
 13. The method of claim8, wherein flushing the test fluid comprises flushing the test fluidusing a fluid or a gas.
 14. A method comprising: mounting an integratedelectro-microfluidic probe card to a device area on a bio-sensor devicewafer, wherein the electro-microfluidic probe card has a first majorsurface and a second major surface opposite the first major surface, andthe electro-microfluidic probe card comprises a transparent portion;electrically connecting at least one electronic probe tip extending fromthe first major surface to a corresponding conductive area of the devicearea; placing a first test fluid on the device area, wherein the placingof the test fluid comprises stamping or printing, and the test fluidplaced on the device area is removable; measuring via the at least oneelectronic probe tip a first electrical property of one or more bio-FETsof the device area based on the first test fluid; and removing anentirety of the first test fluid from the device area.
 15. The method ofclaim 14, wherein removing the first test fluid from the device areacomprises flushing the device area with fluid.
 16. The method of claim15, further comprising placing a second test fluid on the device area,wherein the second test fluid is different from the first test fluid.17. The method of claim 16, wherein the placing of the second test fluidcomprises stamping or printing the second test fluid.
 18. The method ofclaim 16, further comprising measuring via the at least one electronicprobe tip a second electrical property of the one or more bio-FETs ofthe device area based on the second test fluid.
 19. The method of claim18, further comprising marking the device area based on results of themeasuring of the first electrical property and the measuring of thesecond electrical property.
 20. The method of claim 19, wherein themarking comprises physically marking the device area.